This invention relates to an occlusion device for the closure of physical apertures, such as vascular or septal apertures. More specifically, this invention relates to an occlusion device for the heart having a support hoop which allows the device to form a better seal around the aperture and evenly distributes pressure to the tissue surrounding the aperture.
The heart is generally comprised of four chambers, the left and right atrium and the left and right ventricle. Separating the left and right sides of the heart are two walls, or septa. The wall between the two atria is the interatrial septum, and the wall between the two ventricles is the interventricular septum. There are several defects which can affect the septa of both children and adults, including patent ductus arteriosus, patent foramen ovale, atrial septal defects (ASDs), and ventricular septal defects (VSDs).
Normally, permanently repairing certain cardiac defects in adults and children requires open heart surgery, a risky, expensive, and painful procedure. To avoid the risks and discomfort associated with open heart surgery, modern occlusion devices have been developed that are small, implantable devices capable of being delivered to the heart through a catheter. Rather than surgery, a catheter inserted into a major blood vessel allows an occlusion device to be deployed by moving the device through the catheter. This procedure is performed in a cardiac cathlab and avoids the risks and pain associated with open heart surgery. These modern occlusion devices can repair a wide range of cardiac defects, including patent foramen ovale, patent ductus arteriosus, atrial septal defects, ventricular septal defects, and may occlude other cardiac and non-cardiac apertures.
There are currently several types of occlusion devices capable of being inserted via a catheter including button devices, collapsible umbrella-like structures, and plug-like devices. Occlusion devices with umbrella-like structures use a system of small metal wires to hold the occlusion device in place. Once deployed, some of the metal wires may experience more or less stress as a result of the uneven topography surrounding the defect. In such cases, the wires which experience a high static load due to their placement experience high degrees of stress. Several problems may result from this continuous stress, including fatigue failure of the wires which causes them to fracture or break. Broken wires increase the likelihood of damage to the surrounding tissue and lead to patient anxiety.
Another issue caused by the wires is the distribution of pressure along the wires and at their tips. The wires must provide enough pressure against the adjacent tissue to ensure the occlusion device remains in place and that it properly occludes the defect. However, if the wires are not seated properly, or are experiencing high static load due to their placement over uneven topography, the increased pressure may damage the surrounding tissue. In addition, the pressure tends to be highest at the tips of the wires, which may result in the tips poking through tissue or causing damage to it.
Another potential problem with these devices is failure to provide a good seal at the defect. Lack of a good seal can be caused when the wires do not seat properly, or in cases where one or more of the wires pokes back through a defect. If an occlusion device does not provide a good seal, blood will continue to flow through the defect even after the occlusion device has been deployed. Occlusion devices that fail to provide a good seal fail to eliminate health concerns associated with the cardiac defects that they are supposed to treat.
Thus, there is a need in the art for an occlusion device that will effectively occlude cardiac defects and distribute static pressure, thereby increasing the life of the device and sealing ability while reducing the likelihood of damage to the surrounding tissue.